While Platt and McCoy believed they have isolated one component of the neural machinery of risk, they do not believe they have mapped the entire circuitry.
"We don't think the posterior cingulate cortex is by any means the only area that's important for assessing risk, for deciding what's valuable and for actually making a choice based on that valuation," said Platt. "We think that this is just part of a whole circuit that's involved in that process." However, he said, pinpointing a key region involved in risk assessment will enable further studies to map that circuitry.
"It's going to be interesting to trace this circuitry to see which parts of the brain are signaling something about subjective utility and which parts of the brain are signaling information about true reward and punishment experiences," said Platt.
He emphasized that such animal studies are a highly useful complement to human studies and genetic studies using mice. Neuroimaging studies in humans performing such tasks can identify brain regions involved in making decisions based on risk, he said.
"And then, using these animals, we can do electrophysiological studies that allow us to understand how the fundamental processing units of the brain -- single nerve cells -- actually process information about reward and risk and uncertainty; and how that information might contribute to the actual decision process that results in the monkey's choice," said Platt. What's more, he said, the monkey studies allow manipulation of the circuitry using drugs to determine how the circuitry might malfunction in human disorders.
"For example, it is believed that people who have low levels of the neurotransmitter serotonin
Source:Duke University Medical Center